Airbags, particularly combined with seatbelts, have been widely used in automobiles to increase vehicle occupant safety. One approach to improving airbag deployment is to use a sensor to monitor airbag deployment and, depending on certain detected conditions, such as, for example, the airbag prematurely impacting with an object, venting the airbag. Using such a sensor in combination with an airbag to control airbag deployment is a distinct departure from typical past practices where sensors and logic are future looking in order to assess whether and with what force level an airbag should be deployed. Once the decision to deploy and the deployment level are decided by a conventional airbag deployment system, one or more squibs are fired and the airbag deploys.
Technology solutions that integrate one or more sensors that can control venting of the airbag during airbag deployment present a problem in interfacing with conventional design airbag crash controllers. In a typical airbag the only electronic component is the squib initiator. The airbag crash controller performs periodic built-in tests on the squib or squibs associated with the airbag to determine that the nominal resistance of the squib is still within specified limits. Such testing is typically performed at least each time the vehicle is started, and, if an airbag squib resistance is outside the specified limits, the vehicle operator is notified of a fault, and advised to seek maintenance. The airbag crash controller during a crash provides an initiation pulse of energy that activates the squib and deploys the airbag. Deployment sensors with their electronics, logic, and control functions, provide a whole new level of functionality that a conventional airbag crash controller is not designed to test or to function with.
Furthermore, with a conventional airbag module, the interface between the airbag crash controller and the airbag module consists of the two basic functions of resistance checking and initiation pulse, which allows independent design and even procurement of different airbag modules used with the same controller or even in the same vehicle model.
What is needed is a way of adding the functionality of an airbag deployment sensor and controlled venting to an airbag module while preserving the simplicity of the existing interface with the airbag crash controller.